1. Field of the Invention
The present invention relates to a symmetrical viscosity sensor, and in particular, to a symmetrical viscosity sensor for measuring the viscosity of fluids such as transmission oil or engine oil, in which the torsion oscillators are arranged symmetrically on both sides so that the viscosity may be measured effectively due to oscillations within the elastic range as the sensing effective areas increase.
2. Description of the Related Art
Generally, a viscosity sensor for measuring the viscosity of transmission oil or engine oil is mounted in an oil path. The viscosity sensor can be used to indicate when the oil should be replaced.
Japanese Laid-Out Patent No. 1978-107881 describes a viscosity measuring apparatus in which the oscillation plates of a circle shape are arranged oppositely, and the U.S. Pat. No. 6,247,354 describes a sensor for detecting the fluid property in which the resonators of the piezoelectric plate functioning as a sensor unit are formed as a pair.
In addition, Japanese Publication Patent No. 1994-148055 describes a viscosity measuring apparatus in which an oscillation unit corresponding to a sensor unit is formed as a pair. But, since each oscillation unit of these patents generates simple oscillation, there is a drawback that the viscosity measuring results for the fluids are not accurate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.